1. Technical Field
The present invention relates generally to currency processing machines, and more specifically to a system and method for assessing the fitness of notes by recording images of the notes using multiple modes of illumination that facilitate optimal imaging of specific features.
2. Description of Related Art
Automated, high-volume currency processing is a growing international industry affecting numerous aspects of the distribution, collection, and accounting of paper currency. Currency processing presents unique labor task issues that are intertwined with security considerations. It requires numerous individual tasks, for example: the collection of single notes by a cashier or bank teller, the accounting of individual commercial deposits or bank teller pay-in accounts, the assimilation and shipment of individual deposits or accounts to a central processing facility, the handling and accounting of a currency shipment after it arrives at a processing facility, and the processing of individual accounts through automated processing machines. Any step in the process that can be automated, thereby eliminating the need for a human labor task, saves both the labor requirements for processing currency and increases the security of the entire process. Security is increased when instituting automated processes by eliminating opportunities for theft, inadvertent loss, or mishandling of currency and increasing accounting accuracy.
A highly automated, high-volume processing system is essential to numerous levels of currency distribution and collection networks. Several designs of high-volume processing machines are available in the prior art and used by such varied interests as national central banks, independent currency transporting companies, currency printing facilities, and individual banks. In general, currency processing machines utilize a conveyer system which transports individual notes past a series of detectors. By way of example, a note may be passed through a series of electrical transducers designed to measure the note's width, length, and thickness. The next set of sensors could be optical sensors recording the note's color patterns or serial number. Detectors can likewise be used to detect specific magnetic or other physical characteristics of individual notes.
High volume currency processing machines typically pull individual notes from a stack of currency through a mechanical conveyer past several different detectors in order to facilitate the sorting of the individual notes and the accumulation of data regarding each note fed through the machine. For example, a currency processing machine can perform the simple tasks of processing a stack of currency in order to ensure that it is all of one denomination with proper fitness characteristics while simultaneously counting the stack to confirm a previous accounting. A slightly more complex task of separating a stack of currency into individual denominations while simultaneously counting the currency can be accomplished as well.
On the more complex end of prior art currency processing machines, a stack of currency consisting of various denominations can be fed into the machine for a processing that results in the separation of each denomination, a rejection of any currency that does not meet fitness specifications, the identification of counterfeit bills, and the tracking of individual notes by serial number.
Determining the fitness of currency notes is a top priority of both central banks and major money center banks. The goal of monetary authorities is to keep in circulation only those bills that meet specific fitness criteria (e.g., soiling, ink wear). Traditionally, central banks have made fitness determinations themselves. However, more and more of this work is being pushed onto large money center commercial banks that process large volumes of currency.
Monetary authorities are confronted with the difficult balancing act of setting criteria that will minimize the number of unfit bills that remain in circulation while also minimizing fit bills that are mistakenly removed from circulation (the classic type 1 and type 2 errors). This difficulty is compounded by the fact that the physical characteristics of currency bills might vary slightly depending on their source of production (this is particularly true of the Euro, which is a multinational currency). As such, perfectly fit notes produced in one location may be erroneously pulled from circulation by a bank in another location because it falls outside the parameters of the fitness tests used by the banks. The unnecessary destruction of fit currency notes results in millions in losses to central banks every year.
A large contributor to this problem is the limitation of current technology used for determining fitness. For example, imaging technologies currently in use can have trouble determining the degree of soiling or ink wear on a bill. Variations in printing ink may make a bill appear darker and more soiled than it is depending on the parameters and calibration of the imaging device. Another example relates to the physical integrity of the note. A common problem confronting current imaging technology is the use of transparent adhesive tape to repair torn bills. As material science has continued to improve, transparent tape has become more and more clear and harder to detect visually.
Another factor contributing to the difficulty of determining fitness lies in the parameters and tests themselves that are typically employed. The testing standards today are based largely on the technical limitations of older technology. The physical characteristics and parameters that are currently tested were chosen mainly by default because that was what the technology at the time was capable of detecting. Over time these de facto standards have become official standards with which new technologies must now comply, despite the ability to employ newer more reliable parameters.